RAD51 and RAD54, but not RAD50, are required for the preferential repair of the TS in the haploid G2/M cells. WT, rad50Δ, rad51Δ, and rad54Δ cells were synchronized in G1 or G2/M, UV-challenged with 200 J m−2 (B, C) or 100 J m−2 (D) and then reincubated for repair. (A) FACScan analysis showing G2/M synchronized rad51Δ cells. (B) Autoradiograms, the legends are as in Figure 1. (C, D) Quantitative analysis, performed as described in Figure 1D. Each error bar represents the standard deviation of three experiments.